1. Field of the Invention
The present invention relates to a sensor system in which a plurality of sensor bodies of a number of head separation type sensors (for example, fiber type photoelectric sensors, ultrasonic sensors, proximity sensors and the like) are arranged aligned with each other by means of a DIN (Deutsche Institute Normenausschuss) rail or the like.
2. Description of the Background Art
In the technical field of FA (Factory Automation), for example, head separation type sensors (for example, fiber type photoelectric sensors, ultrasonic sensors, proximity sensors and the like) are widely used to detect presence/absence and positions of objects. When a fiber type photoelectric sensor is used, for example, a sensor head for emitting and receiving a detection beam (red light beam, infrared ray or the like) is placed in a narrow space near an object of detection, while a sensor body containing a light emitting element and a light receiving element is accommodated in a control panel placed away from the object of detection, with the sensor head and a sensor body coupled by an optical fiber. Generally, the outer shape of the sensor body casing is a thin rectangular cube. When a number of sensor bodies are to be accommodated in the control panel, the bodies are typically arranged in contact with each other to form a row, using the DIN rail.
FIG. 17 schematically shows an example of a sensor system in which sensor bodies of fiber type photoelectric sensors (hereinafter simply referred to as xe2x80x9csensor bodiesxe2x80x9d) are arranged in contact with each other to form a row. As can be seen from FIG. 17, a plurality of sensor bodies 402 for detecting different objects are arranged in a row in the transverse direction on a DIN rail 401 mounted in the control panel. From a front surface of each of the sensor bodies 402, optical fibers 403 and 404 constituting outgoing and returning paths for the detection beam, respectively, are drawn out, and from the rear end surface of the case, an electric cord 405 including a power feed line 405a and a signal line 405b (see FIG. 18) is drawn out.
When a detection beam path 408 is opened for transmission or intercepted between sensor head portions 403a and 404a at the tip ends of optical fibers 403 and 404, internal circuitry of the sensor body functions, and a detection signal (a switching signal or an analog signal corresponding to the amount of received light) is externally output through the signal line 405b in the electric cord 405. The detection signal is supplied as a control
Further, as shown in FIG. 18, power supply from a power source 406 to each of the sensor bodies 402 is effected through the power feed line 405a. Power feed line 405a includes two, that is, positive and negative, lines.
In this manner, in the conventional photoelectric sensor systems in which a number of sensor bodies 402 are arranged aligned with each other and in contact with each other, it is necessary to supply power to each of the photoelectric sensor bodies 402 through power feed line 405a in the electric cord. Therefore, for the electric cord, a cord having a large number of core lines is necessary, and, in addition, it takes time and labor just to connect these lines.
A structure saving lines in this type of photoelectric sensor system has been known, as described in Japanese Patent Laying-Open No. 9-64712. According to the technique described in this Laid-Open Application, the sensor system includes one main sensor (body) and a plurality of sub sensors (bodies) arranged in a row and in contact with the main sensor and with each other. An electric cord including both the signal line and the power feed line is main sensor, and an electric cord including the signal line only is connected to each sub sensor, by joining means that will fix the position such as solder. On the side surfaces of the cases of the main and sub sensors, there are a male junction and female junction to provide interface between neighboring sensors. When the main sensor is connected to a sub sensor and the neighboring sub sensors are connected to each other by connected to the these joints, the power supplied to the main sensor through the electric cord is successively passed through a conductor in each sensor case, to the series of sub sensors.
In the sensor system described in Japanese Patent Laying-Open No. 9-64712, feeding and receiving of power through the conductors in the sensor cases through the male and female joints connecting the neighboring sensor bodies with each other is possible, whereby the reduction of lines can be achieved, as power supply to individual sub sensor through the electric cord is made unnecessary.
In such a sensor system, however, two different sensor bodies, that is, one having such a structure that receives external power through the electric cord, and one having such a structure that receives power through the male and female joints from the neighboring sensor body are necessary. This means that the number of parts and the steps of parts management increase, resulting in increased cost. Further, inventory management of the sensor bodies is troublesome, as there are two different types of the sensor bodies.
Further, when trouble occurs in any of the sensors (main or sub), it becomes necessary to change the electric cord connected to the defective sensor at the same time. This requires time consuming and troublesome work of disconnecting the bundle of electric cords and newly connecting substitute electric cords, and material waste increases.
An object of the present invention is to provide a sensor system which can significantly reduce the number of power feed lines in the overall system, which enables a decrease in costs and simplified inventory management by adopting sensor bodies of common structure not distinguished for the main or sub sensor, and, in case any malfunction occurs in any of the sensor bodies, enables exchange of the defective sensor body only, while the electric cords that have been used so far can be maintained.
Another object of the present invention is to provide a connector system which can flexibly cope with increase/decrease of the number of sensors arranged, when a plurality of sensor bodies are to be arranged in a row, and which can maintain minimum number of power feed lines regardless of the number of sensors to be arranged.
A further object of the present invention is to provide a main connector suitable for implementing the above described power feed connector system.
A still further object of the present invention is to provide a sub connector suitable for implementing the above described power feed connector system.
The above described objects can be attained by the sensor system in accordance with the present invention, including a plurality of sensor bodies arranged aligned and adjacent to each other, and a plurality of connectors detachably coupled to the sensor bodies and detachably coupled to neighboring connectors.
Here, xe2x80x9csensorxe2x80x9d includes head separation type sensors such as a fiber type photoelectric sensor, an ultrasonic sensor, a proximity sensor and the like. Generally, the sensor system of this type consists of the sensors of the same type. The present invention, however, is also applicable to a sensor system in which various sensors mentioned above are used mixed with each other.
The sensor body is provided with a joint for the connector enabling detachable coupling with the corresponding connector, and the connector is provided with a joint for the sensor body enabling detachable coupling with the corresponding sensor body.
The xe2x80x9cjoint for the connectorxe2x80x9d on the sensor body includes at least a power receiving terminal for receiving, from the connector, the power to be fed to the internal electric circuitry. Here, xe2x80x9cat leastxe2x80x9d means that there may possibly be one, two or more signal terminals in addition to the power receiving terminal.
The xe2x80x9cjoint for the sensor bodyxe2x80x9d on the connector includes at least a power feed terminal for feeding power to the internal electric circuitry of the sensor body. Here again, xe2x80x9cat leastxe2x80x9d is used to include possible additional terminals.
The sensor body and a connector are detachably coupled through the joints of each other. When the sensor body and a connector are coupled, the power receiving terminal of the joint for the connector is electrically connected to the power feed terminal of the joint for the sensor body. Thus, a power feed path from the connector to the sensor body is established.
Preferably, the direction of attachment/detachment when a sensor body and a connector are coupled is orthogonal to the direction of coupling between the sensor bodies with each other. This arrangement facilitates attachment/detachment between the sensor body and a connector, without the necessity of providing a large space between the sensors. Further, it may be preferred if a specific sensor body is detachable, while the coupled state of the connector is maintained.
Here, xe2x80x9ca plurality of connectorsxe2x80x9d includes at least one main connector and one or two or more sub connectors. In other words, there may be two or more main connectors.
The main and sub connectors are provided with a joint for neighboring connector, enabling detachable coupling with the neighboring connectors.
The xe2x80x9cjoint for the neighboring connectorxe2x80x9d of the main connector includes at least a power feed terminal for supplying the power introduced from the power supply line to a neighboring connector.
The xe2x80x9cjoint for the neighboring connectorxe2x80x9d of the sub connector includes a joint for the neighboring connector including at least a power receiving terminal for receiving power from one neighboring connector, and a joint for the neighboring connector including at least a power feed terminal for feeding the power received by the power receiving terminal to another neighboring connector.
The neighboring connectors are detachably coupled through the joints for the reciprocal neighboring connectors. At this time, the power feed terminal provided in the joint for the neighboring connector of one connector is electrically connected to the power receiving terminal provided in the joint for the neighboring connector of the other connector. Thus, a power feeding and receiving path from one connector to the other connector is established.
More specifically, the main connector and a sub connector are detachably coupled through the joint for the neighboring connector of the main connector and the joint for the neighboring connector of the sub connector. At this time, the power feed terminal of the main connector is electrically connected to the power receiving terminal of the sub connector. Thus, a power feeding and receiving path from the main connector to the sub connector is established.
The sub connector coupled to the main connector and another sub connector adjacent to this sub connector are detachably coupled through the joints for the neighboring connectors of themselves, and at this time, the power feed terminal of that sub connector which is next to the main connector is electrically connected to the power receiving terminal of that sub connector which is next to the sub connector.
By successively coupling one or a plurality of sub connectors to at least one main connector, a row of connectors is formed, and a series of power feeding and receiving path starting from the main connector is established.
Preferably, the joint for the neighboring connector of the main connector is provided on the side surface only on which a neighboring connector exists, and not on the other side surface. Therefore, when the main connector is arranged at an end of a row of sensors, the power feed terminal is not exposed at the side where the neighboring connector does not exist. Therefore, the risk of an electrical short-circuit or receiving an electric shock by accidentally touching the power feed terminal can be avoided.
Each joint for the neighboring connector of the main and sub connectors has a connecting structure for establishing mechanical and electrical connections with the neighboring connector. Here, the power receiving terminal and the power feed terminal of each joint for the neighboring connector are included in the connecting structure for establishing the electrical connection.
Preferably, the connecting structure of the joint for the neighboring connector including a power receiving terminal of the sub connector preferably has a projecting portion protruding to a connector neighboring the joint. The connecting structure of the joint for the neighboring connector of the main connector and of the joint for the neighboring connector of the sub connector including the power feed terminal has a recessed portion receiving the projecting portion of the connector neighboring the joint, and the connecting structure does not have the projecting portion protruding toward the neighboring connector. In such a structure, the connecting structure of connector does not protrude from either end of the row of sensors. As there is no projection on either end of the row of sensors, it becomes possible to arrange other device not requiring power connection by the connector in tight contact with the row of sensors. Further, the situation where an operator""s clothes or the like are accidentally caught on the projection or something hitting the projection can be avoided.
The main connector is connected to an electric cord including at least a power feed line, and the main connector includes an internal conductor for leading the power supplied from the electric cord to the power feed terminal provided at the joint for the sensor body and to the power feed terminal provided at the joint for the neighboring connector, inside the main connector.
More specifically, in the main connector, the power introduced from the electric cord is supplied through the internal conductor to the power feed terminals of the joint for the sensor body and a joint for the neighboring connector and further, the power is passed to the sensor body and to the power receiving terminal of the neighboring sub connector, from the power feed terminals.
Further, the sub connector includes an internal conductor for leading the power received through the power receiving terminal provided at one joint for the neighboring connector to the power feed terminal provided at the joint for the sensor body and to the power feed terminal provided at the other joint for the neighboring connector, within the sub connector.
More specifically, in the sub connector, the power received by the power receiving terminal is supplied through the internal conductor to the power feed terminal provided at the joint for the sensor body and to the power feed terminal provided at the joint for the neighboring connector, and further, from these power feed terminals to the neighboring connector and the power receiving terminal of the sensor body.
In this manner, by coupling an arbitrary number of sub connectors to the main connector, it becomes possible to feed the power fed to the main connector through the electric cord to each sensor body through the row of connectors.
The sensor system of the present invention provides a power feed line by means of a connector system including a main connector to which an electric cord including at least a power feed line is connected, and one or a plurality of sub connectors electrically connected to the main connector. Therefore, simply by coupling the main connector and the sub connector to the sensor bodies and by coupling neighboring connectors with each other, the power can be supplied to each sensor body. Therefore, the power feed line have only to be connected to the main connector, and hence the power feed line is unnecessary for the sub connectors. Therefore, the number of lines for the overall system can be reduced.
Further, as the connector and a sensor body can be detachably coupled, it is possible, when any trouble occurs in the sensor body, to detach the sensor body from the corresponding connector, and to solve the problem simply by exchanging the sensor body. More specifically, re-connection of electric cords and a control equipment such as the PLC and associated works of binding of the lines when the sensor body is exchanged in the conventional system, can be avoided.
Further, if it is made possible to draw out the sensor body from the connector while maintaining coupling of adjacent connectors with each other, even when the aligned arrangement of the sensor bodies in the system is disconnected because of a failure of any sensor body, for example, power feed to the sensor bodies succeeding the defective portion is continued.
The connector system of the present invention is also applicable for power connection between sensors of the same type but of different specifications, as in the case of photoelectric sensors in accordance with different specifications, as well as to power connections of sensors of different types, as in the case of a photoelectric sensor and a proximity sensor. In such a case, what is necessary in designing the sensor body is simply to consider the position of the connector, so as to enable connection between neighboring connectors with each other.
When the connector system of the present invention is applied, limitations in the design of the sensor body as expected when the structure for electrical connection with an adjacent sensor body is to be provided on the sensor body itself, can be eliminated.
The sensor body designed corresponding to the connector system of the present invention may be used connected to the main connector and not electrically connected to other sensors. In such a case, the sensor may be used as a sensor having similar function and appearance to the conventional sensor to which the electric cord is detachably attached.
The sensor body designed corresponding to the connector system of the present invention may be used connected to the connector of the conventional structure not having the connecting structure with the neighboring connector. In this case, the electrical connecting structure to the neighboring sensor unnecessary in such use, is absent.
As described above, as the electrical connecting structure is provided in the connector, the user of the sensor can flexibly select an optimal system dependent on the intended use, using the sensor body standardized to be used with the connector system of the present invention.
In a preferred embodiment of the present invention, in addition to the power feed line, one or two or more signal lines are included in the electric cord introduced to the main connector, and corresponding number of signal terminals are provided at the joint for the sensor body of the main connector. Further, the main connector includes therein an internal conductor connecting respective ones of the signal lines of the electric cord to the corresponding signal terminals on the side of the joint for the sensor body, respectively.
Further, an electric cord including one or two or more signal lines is introduced to the sub connector, and the corresponding number of signal terminals are provided at the joint for the sensor body of the sub connector. Further, the sub connector includes therein an internal conductor coupling the signal lines of the electric cord with the corresponding signal terminals at the side of the junction for the sensor bodies, respectively.
Therefore, each connector provides, in addition to the power feed function for the sensor body, the function of connecting the signal terminals in the sensor body with the signal terminals in the electric cord.
More specifically, it becomes possible to feed power to the sensor body and to transmit/receive a signal between the sensor body and a control device such as a PLC, through the connector.
Further, in this case also, the connector and a sensor body is detachably coupled. Therefore, when there is a trouble in the sensor body, it is possible to detach the corresponding sensor body from the corresponding connector, and to exchange the sensor body only, and the trouble is eliminated. More specifically, re-connection between the electric cords and a control device and the like and associated binding when the sensor body is exchanged in the conventional system, can be avoided.
Further, in a sensor system in which exchange of signals between adjacent sensor bodies is possible, drawing out the electric cord for signal output from each sensor becomes unnecessary. In that case, the sub connector will be simply a connector used for power feed only.
As described above, according to the present invention, the power feed line is unnecessary for the connectors other than the main connector. Therefore, the number of power feed lines can significantly be reduced for the overall system. Further, because sensor bodies having the same structure are employed for both the main and sub sensors, the cost can be reduced and inventory management is made easier. Further, if a failure occurs in any of the sensor bodies, it is possible to simply exchange the defective sensor body only, while maintaining the electric cords used up to that point in time.
Further, according to the present invention, when a plurality of sensor bodies are arranged in a row and in contact with each other, the number of sensors to be arranged can be flexibly changed, and the minimum number of power feed lines can be maintained regardless of the number of sensors to be arranged.